And unlike the billionaire founders of Google - Larry Page and Sergey Brin - he promises to never buy a super yacht. "While they have big yachts I have an inflatable dinghy that I take to lakes. Ego consumption is not appropriate in a world where there's climate change."
Christian would, in fact, struggle to buy a yacht if he ever wanted one, as he put two legally binding restrictions on the business - shareholders and staff cannot personally sell shares or take profits outside of the company.
However, his world view changed when aged 18 he went travelling for three months through India. "I met smarter people than me who didn't have the same opportunities because they weren't born in Germany," he says. "It started dawning on me that maybe I should do something to make the world a better place."
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After university he spent six months in Nepal in 2007, where he first tried and failed to launch a search engine to raise funds for local charity and non-government projects. "I didn't know how to launch a business, funds were limited, and most days there were internet and electricity issues."